29-01-2021· Sell your old moving boxes on the U-Haul Box Exchange to other families that will be moving soon. You can also use the exchange to look for free boxes as some sellers will give their boxes away for free. 4. eBay. Many people are selling their used cardboard boxes on eBay. Whether you have used Amazon boxes, moving boxes, brand new boxes to sell, they can all list on eBay.